The data receiving system used in the Spread Spectrum communication system or the Code Division Multiple Access communication system uses at present a matched filter, sliding correlator, or the like. When a receiving device uses a matched filter, the output signal is given by analog values; accordingly, the receiving device needs an analog/digital converter (A/D converter).
When the data transfer rate of a modulated signal is as high as several gigabits/second (several G bps), the highest processing rate of the A/D converter at present is about 100 MHz. Therefore, if it is intended to execute an A/D conversion to the analog signal of several GHz, lots of A/D converters have to be used in parallel. This consequently expands the circuit scale of the receiving device and so forth, which is a problem to be solved.